No abstract

Staphylococcus aureus produces a variety of toxins, enzymes, and metabolites, among which are enterotoxins A and B, exotoxins associated with certain outbreaks of food poisoning (2). Recent reports have established the lethal nature of enterotoxin B after its intravenous injection, with death in experimental animals characterized by profound shock (3-5). Fever and several other toxic manifestations of intravenously administered staphylococcal enterotoxin B (SEB) resemble those of bacterial endotoxin (6-10). In view of a possible etiologic relationship of staphylococcal enterotoxin to the shock syndrome of staphylococcal sepsis, there has been surprisingly little investigation of intravenously administered enterotoxin.The purified toxin produced by Schantz and coworkers (11) has been characterized extensively. It was shown to be a simple protein, free of any detectable lipid or carbohydrate, having a molecular weight of approximately 35,000. Electrophoretic studies revealed its migration as a single component with an isoelectric point of pH 8.6. Serologic studies by means of the Oudin and Ouchterlony techniques indicated greater than 99%o homogeneity. It will withstand a temperature of 60°C for 16 hours without loss of toxicity.Previous work performed in our laboratory showed that SEB was cleared rapidly from the blood of experimental animals (4). It was observed further that animals surviving an initial challenge appeared to clear SEB at a somewhat slower rate after a second challenge. In contrast, * Submitted for publication September 28, 1965; accepted May 23, 1966.A portion of this work appeared in abstract form (1). In conducting the research described in this report, the investigators adhered to the principles of laboratory animal care as established by the National Society for Medical Research. other investigators have shown that the phenomenon of tolerance and immunity to bacterial endotoxins are characterized by increased, rather than delayed, rates of clearance (12, 13). In view of certain similarities in the toxic manifestations of these two bacterial products it seemed paradoxical that a degree of immunity might alter their clearance kinetics in opposite directions.The present report extends observations on the clearance rate of labeled SEB from the circulation of rhesus monkeys and demonstrates the marked alterations in clearance rate produced by acutely administered type specific antitoxins. MethodsAnimals. Healthy Macaca mulatta (rhesus) weighing 2.5 to 3.5 kg were placed at least 1 week preceding investigation in restraining chairs 'specially designed to permit study in a nonanesthetized state. These animals had no known previous experience with SEB, and each was used for only a single challenge with this toxin. On the day before study bilateral indwelling saphenous vein catheters were inserted, one to permit injection of the test materials and the second to allow repeated blood sampling.Labeling and administration of toxin. The highly purified SEB as described by Schantz (11) was isotopically lab...

The protein toxin staphylococcal enterotoxin B (SEB) produces a clinical syndrome somewhat similar to that of gram-negative endotoxins. Our studies indicate a further similarity to endotoxin in that SEB is rapidly cleared from the plasma of monkeys. However, data reported herein show that an effective Thorotrast blockade of the reticuloendothelial system (RES) does not produce a significant change in the rapid disappearance kinetics of SEB. This observation contrasts with what is known regarding endotoxin clearance. Furthermore, other data reported herein indicate that acute bilateral renal artery ligation produces a profound delay in SEB clearance from plasma. A possible mechanism for renal degradation of SEB is theorized. The RES may play a less important role in the clearance of SEB. This finding contrasts with the demonstrated importance of the RES in clearance and detoxification of gram-negative endotoxin.

A highly purified preparation of staphylococcal enterotoxin B was administered intravenously, 1 mg/kg, to rhesus monkeys. Electroencephalograms (EEG) were recorded from electrodes attached to the skin or implanted on the dura. The dose of toxin employed consistently produced a sequence of vascular collapse followed by death; in control studies. animals were bled periodically to produce a similar pattern of shock. Regardless of the time to death following administration of the enterotoxin, there were essentially no changes from base line EEG patterns until shortly before death. With the development of preterminal severe shock, there was a marked decrease in EEG wave frequency and an initial increase in amplitude. The latter diminished progressively to produce an isoelectric tracing immediately prior to death. This could be reversed for a brief period by epinephrine. An identical sequence of EEG changes was observed during the terminal period of hemorrhagic shock. It is postulated that cerebral anoxia, caused by inadequate blood flow, is the primary cause of the altered EEG patterns that accompany enterotoxin toxicity. In this respect, staphylococcal enterotoxin B produces changes apparently similar to bacterial endotoxin but distinctly different from the EEG effects reported after botulinum toxin, anthrax toxin, or rattlesnake and cobra venom.

No abstract